More information about build depnedencies.

Swap-stack and ROP frames can pass double values in addition to integer
values.

Added more examples to test double value passing.

Updated README file.

Reorganised Makefile and removed things that are no longer relevant.

Redefined what consists of a ROP frame on x64.  This is consistent with
aarch64.

Just in case when the user want libyugong in a dynamic library.